1. Field of the Invention
This invention relates to catheters having electrodes for introduction into the body and, more particularly, to catheters having electrodes for performing radio frequency (RF) ablations in the body.
2. Description of the Related Art
Catheters for RF ablation have heretofore been provided. However, difficulties have been encountered with such catheters in that it has been difficult to achieve lesions of sufficient size. Increasing the RF power to the catheter in an attempt to increase the size of the lesions has caused degradation of the blood in the region where ablation is taking place and resulting products of the degradation to be deposited on the electrode surface so as to undesirably increase the inpedance of the electrode. Such deposition is particularly acute at points where electrical conductors and electrical insulators meet and form heat risers. Conductive skirts proposed to mitigate these heat risers, for example as disclosed in U.S. Pat. No. 5,230,349, have proven difficult and expensive to manufacture. In addition, it has been found that increased power levels create undesirable heating of the blood which can create blood clots. There is, therefore, a need for a new and improved catheter for RF ablation which overcomes these disadvantages.